Juvenile grass carp are generally fed 3-5 meals per day at a daily ration of 3-5 percent of body weight (Ni and Wang, 1999). Daily feeding rates are normally adjusted according to the physiological condition of the fish, temperature and weather conditions. Automatic feeders are normally used for pond or cage culture. One or several feeding platforms are established in the pond according to pond size (Figure 2). Grass carp are easily trained to feed efficiently. This is achieved by beating the feed bucket or feeding machine (Figure 3) to attract the fish. Pellet size is adjusted according to mouth gape (Table 13) (Zhao and Yang, 2000).
Many farmers develop their own feeds and feeding methods. For example, some farmers feed grass carp fry of 30mm TL (stocked at 6 000 fry/1 000 m2) on bean curd by-products for one week and then switch to duckweed at 60-128 kg duckweed/1 000 m2. After 20 days the fish grow to around 70 mm (total length) and the quantity of duckweed is adjusted according to fish biomass. After 4 months the diet is switched to terrestrial grasses (Liang, 2002).
